Study On The Radio-Over-Fiber-Based Wireless Mdobus Networks For Industrial Automation Applications

As the rapid improvement of information technology and network technology, intelligentizing industrial automatic control network becomes a unavoidable trend. In recent years, wireless communication technology slowly infiltrated into the field of industrial automatic control, while traditional Modbus protocol of application industrial control area has some limitations confronting current complex and fickle live environment. Increasing amount of new network users and requirement of the bandwith leads to the shortage of current available wireless spectrum resources, then, RoF technology slowly getting on the stage of the new century.This paper proposed an433MHz wireless Modbus protocol based on RoF technology, which provided industrial automatic control network with an transmission method combining light and wireless. This proposed protocol also realized high speed, flexible, secure and independent communication and network coverage, and completed wireless data collect and central control, furthermore, it promoted the intelligent, automatic, networked, and integrated development of industrial automation field. This paper’s main works are as follows.1. The research of traditional Modbus protocol and wireless Modbus protocolThis paper introduced traditional Modbus protocol in detail from the aspects of communication principle, information frame structure, communication protocols and error checking method. Then, it proposed a Modbus protocol based on433MHz wireless module (CC1100module) considering that traditional cable communication methods have limitations in transmitting live data. Loading traditional Modbus protocol to433MHz wireless frequency can greatly enhance its flexibility and convenience, which owns many advantages and features comparing traditional Modbus protocol and has broad prospect of application.2. The design and implement of Wireless Modbus protocolThis paper proposed a system design frame of wireless Modbus protocol, and introduced the master-slave communication mode of wireless Modbus. Then, it provided an overview of the wireless Modbus protocol design’s particular procedure.3. The system design and application of WiFi-Modbus based on RoF technologyThis paper proposed an optical wireless technology and wireless Modbus technology combined networking scheme, combining wireless Modbus protocol design and RoF technology. Furthermore, it provided global scheme, theory and particular experimental result.